(a) Technical Field of the Invention
The present invention relates to a safety for nailing devices, and in particular to a safety that, unless released, prevents the nailing device from operation by blocking a nail striker plate, in order to ensure operation safety of the nailing device.
(b) Description of the Prior Art
A nailing device functions to repeatedly and forcibly feed out nails for fixing different parts or articles together. A regular nailing device comprises a nail striker plate that is arranged inside a housing and movable up and down in a given direction. A strip of nails is accommodated in a bottom portion of the housing and is fed forward by a nail forwarding unit to locate below the striker plate for being struck out of the housing. The striker plate is movable either manually, electrically or pneumatically to a lifted, ready-to-strike position from which the striker plate is release to spontaneously strike out the nail located therebelow. Since the nailing device can be easily operated and provide efficient nailing operation, it has been widely used in for example carpentry.
A conventional nailing device is operated by lifting the striker plate to set the striker plate in a ready-to-strike condition. To avoid undesired operation of the nailing device, taking a manually operated nailing device as an example, a safety ring is provided on the housing of the nailing device to secure, in a releasable manner, an operating handle whereby mistakenly operating the handle to cause undesired percussion of nail can be eliminated. In use of the nailing device, the safety ring must be released to allow the nailing device to be set in a ready-to-strike condition, and therefore inadvertent percussion at the time that the nailing device is not properly set on a work piece may happen, which may hurt the operator or other persons standing nearby by shooting uncontrolled nail.
To cope with such a problem, Taiwan Patent No. 1281432 discloses a nailing device comprising a housing in which a safety bar is movably arranged in such a way that the safety bar is normally projecting out of a bottom of the housing. The safety bar functions to prevent an engaging portion formed on a handle from engaging an opening defined in a striker plate. When the nailing device is properly set on a work piece, the safety bar is forced into the housing, allowing the handle to engage the striker plate for setting the nailing device in a ready-to-strike condition. As such, inadvertent percussion of the nailing device can be avoided.
The known device uses a biasing torque provided by a torsion spring to disengage the engaging portion of the handle from the opening of the striker plate in order to realize prevention of inadvertent percussion. However, when the operator of the nailing device applies a force that exceeds the spring force, the engaging portion of the handle may also get back into engagement with the opening of the striker plate to cause undesired percussion. Apparently, the known device is not capable to fully eliminate the potential risk of inadvertent percussion.
Since the force that strikes the nail out of the housing of the nailing device is very significant, if the nail is undesirably shot to a human body, damage may be resulted. This is even worse if the nail shoots at the eyes, which may lead to loss of sight. Thus, it is important that inadvertent percussion of the nailing device can be definitely excluded unless the nailing device is properly set on a work piece to thereby ensure operation safety of the nailing device.
In view of the above discussion, the present inventor has engaged in researches in the related fields, attempting to ensure an improvement that secures the operation safety of a nailing device by incorporating a novel safety to eventually and completely overcome the problem associated with inadvertent percussion of the conventional nailing devices.